Time synchronization may be important in certain applications, for example, to coordinate different parts in industrial machines, assembly lines, and other sensor and actuator networks. Time synchronization may also be required for Time Division Multiple Access (TDMA) based techniques in communication networks.
In communication networks, the clocks of different nodes may drift due to, for example, crystal inaccuracies. In systems that require time synchronization, synchronization may be achieved by periodically exchanging messages between the nodes. The synchronization message has been implemented in the format of a packet which includes the local time of the sender so that the receiver may set its local time (e.g., its clock) as soon at it receives the packet. The synchronization message may be long and the process energy inefficient. In particular, the packet may be long because it includes headers and several bytes of time information.
An exemplary embodiment and/or exemplary method of the present invention is directed to method of synchronizing a network, which includes transmitting a tone signal to convey time information, and setting a local time according to the conveyed time information.
Another exemplary embodiment and/or exemplary method of the present invention is directed to method of synchronizing a network, in which the signal includes a preamble followed by a start symbol and the local time is set when the start symbol is received.
Yet another exemplary embodiment and/or exemplary method of the present invention is directed to method of synchronizing a network, which includes setting a clock of a receiver to a predefined time when one of the tone signal ends and a predefined pattern within the tone signal is received.
Still another exemplary embodiment and/or exemplary method of the present invention is directed to method of synchronizing a network, in which the signal is a short tone.
Yet another exemplary embodiment and/or exemplary method of the present invention is directed to method of synchronizing a network, in which the network includes wireless sensor nodes.
An exemplary embodiment and/or exemplary method of the present invention is directed to a method for synchronizing a communication network, which includes transmitting a tone signal, detecting an occurrence of a predefined aspect of the tone signal, and setting a local time based on the occurrence of the predefined aspect of the signal.
Another exemplary embodiment and/or exemplary method of the present invention is directed to a method for synchronizing a communication network, in which the predefined aspect is a start symbol and/or the predefined aspect is an ending of the tone signal.
Yet another exemplary embodiment and/or exemplary method of the present invention is directed to a method for synchronizing a communication network, which includes periodically waking up from a sleep cycle to detect the occurrence of the predefined aspect of the tone signal.
Still another exemplary embodiment and/or exemplary method of the present invention is directed to a method for synchronizing a communication network, in which the tone signal is transmitted for at least a period of maximum clock skew between a transmitter and a receiver.
Yet another exemplary embodiment and/or exemplary method of the present invention is directed to a method for synchronizing a communication network, in which the elements of the network form a chain and/or tree topology and the method is repeated.
An exemplary embodiment and/or exemplary method of the present invention is directed to a communication system, which includes a transmitter to transmit a signal to convey time information, and a receiver to receive the signal and set a local time based on the conveyed time information.
Another exemplary embodiment and/or exemplary method of the present invention is directed to a communication system, in which the local time is set when a predefined part of the signal occurs or when the signal ends.
Yet another exemplary embodiment and/or exemplary method of the present invention is directed to a communication system, in which the signal is a tone.
Still another exemplary embodiment and/or exemplary method of the present invention is directed to a communication system, in which the tone includes a preamble followed by a start symbol.
Yet another exemplary embodiment and/or exemplary method of the present invention is directed to a communication system, in which the local time is set when the start symbol is received.
Still another exemplary embodiment and/or exemplary method of the present invention is directed to a communication system, in which the receiver periodically wakes up from a sleep cycle to receive the signal, and the signal is transmitted for at least a period of a maximum clock skew between the transmitter and receiver.
An exemplary embodiment and/or exemplary method of the present invention is directed to an apparatus for synchronizing a communication network, which includes a first arrangement to transmit a tone signal, a second arrangement to received the tone signal, a third arrangement to detect an occurrence of a predefined aspect of the tone signal, and a fourth arrangement to set a local time based on the occurrence of the predefined aspect of the signal.